Internal broaching machine and internal broach

Abstract

A broach for internal broaching is formed on its pull end and / or follower end with a tapered surface machined with high accuracy. A pull head and / or a retrieving head of a broaching machine, which drivingly grip the pull end and the follower end the broach, is formed with a tapered inner surface complementary to the tapered surface of the broach. The pull head and the retrieving head grip the broach while pressing and clamping their tapered inner surface against the tapered surface, and these heads and the broach are firmly connected together. Clearances or gaps between the heads and the broach are thus eliminated, concentricity between the heads and the broach is significantly improved, and broaching can be performed with high accuracy.

Description

BACKGROUND OF THE INVENTION[0001]The present invention generally relates to an internal broaching machine. More specifically, the invention relates to an internal broaching machine which eliminates a gap between a broach and a pull head for gripping a front shank or pull end of the broach and a gap between the broach and a retrieving head for gripping a rear shank or follower end of the broach, thereby improving the accuracy of concentricity of the broach and the heads for a broaching operation.[0002]When performing an inner surface broaching using a broach, a pull head has conventionally been used for holding a pull end of the broach, such as shown in JP-A-6-126526. FIG. 13 shows such a pull head. This pull head has a body 51 formed with an insertion hole 54 for a broach pull end 50 and four claw members 52 arranged radially around an axis of the body 51. The claw members 52 can be advanced into the insertion hole 54.[0003]In operation, the broach pull end 50 is inserted into the i...

AI Technical Summary

Benefits of technology

[0011]The invention has an object of providing an internal broaching machine which can significantly improve concentricity between a broach and a pull head or retrieving head by removing a clearance between the pull head for gripping a broach pull end and the broach in an internal broaching operation, or by removing a clearance between the retrieving head for gripping a broach follower end and the broach.

[0012]Another object of the invention is to provide a broach, which is for use in the above machine and can eliminate a play or gap between it and the pull head or retrieving head.

[0021]With the internal broaching machine of the invention constructed as above, since the heads and the broach are connected by clamping the tapered surfaces with the tapered inner surfaces, the heads and the broach are firmly coupled together. As a result, plays or gaps between the heads and the broach are eliminated, and broaching can be performed with concentricity between the heads and the broach significantly improved, thereby a highly accurate broaching can be performed.

[0022]According to the invention, it is possible to transfer the accuracy of the machine to the cores of the pull head, the retrieving head and the broach and thereby significantly improve machining accuracy of a workpiece compared with that of the previous machining performed before the broaching operation.

Problems solved by technology

The conventional construction thus can not be expected to improve the broaching accuracy and has an adverse effect on the life of the broach.

As described above, with the conventional machine, the broach moves out of its place during a broaching operation and follows the accuracy of previous machining performed on a workpiece before the broaching operation, and correcting cutting by the broach can not be expected.

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